The Mi-17 V5 helicopter had taken off from the Khirmu helipad, near Tawang, and was on its way to Yangste, near the China border, to drop kerosene jerrycans for an Army camp, said SP (Tawang) M K Meena. He added that it crashed around 6.30am.

"The rescue operation was carried out at an altitude of 17,000 feet. All the bodies were recovered and brought to the Khirmu helipad for medical formalities, and then flown to the Tezpur airbase in Assam," the SP said.

Though the court of inquiry ordered into the crash will establish the exact reason for the crash, sources said the kerosene canisters being airdropped by parachute to the forward Army post seemed to have got entangled in the helicopter's tail rotor.

The accident once again underlines the high crash rate that continues to dog the Indian armed forces. Since 2011, the three services have lost over 50 aircraft and 25 helicopters in crashes in which over 90 people have been killed.This includes over 20 fighter jets and six helicopters of the IAF in the last three years.

Speaking in the run-up to the Air Force Day on October 8, Air Chief Marshal B S Dhanoa had said on Thursday the "losses during peacetime are a cause of concern", and corrective measures were being taken to reduce the number of crashes.

SP Meena said a team comprising police personnel and district administration officials had left for the crash site to gather more details.

This is the second IAF helicopter crash in Arunachal Pradesh in three months. On July 4, an IAF advanced light helicopter had crashed at Sagalee, in Papum Pare district, killing all four on board. The helicopter had been deployed to rescue passengers stranded between Sagalee and Itanagar.